TuneIn also today announced that it surpassed 1 billion listening hours for this year in April, making it the top online destinations for live audio content (and likely the #2 online music destination behind Pandora).

As TuneIn’s CEO John Donham told me earlier this week, the company plans to use this new round of financing, which comes less than a year after it raised a $16 million round in 2012, to continue to invest in content and its product.

One area the service is clearly going to focus on is on providing more services for the broadcasters that opt to use its services to get access to online listeners. While Donham didn’t go into details, he did note how many local stations still run the same local ads online, even though the online listener is often anything but local. The company, it seems, may soon allow these broadcasters to substitute their local ads for more targeted messages.

As for adding content on the platform, Donham said that while TuneIn already features quite a bit of content (over 70,000 FM, AM, HD and online radio stations and 2 million on-demand programs), the ultimate goal is obviously to “have everything.”

One group of stations it may have trouble with, though, is Clear Channel’s lineup. Clear Channel, which owns the competing iHeartRadio platform, is using a walled garden strategy in his view, while TuneIn offers an open platform for stations. He does believe, however, that it is still very early in the game (and he cited this new funding round as an example) and that the business is really just starting out to live up to its potential.

TuneIn says it currently has about 40 million active listeners in over 230 countries and territories. It powered 227 million listening sessions of more than 60 seconds in March. The service recently launched its TuneIn Live service and a major redesign on the desktop. The majority of its growth, however, comes from mobile listeners, where it is still experiencing “triple-digit growth,” according to Dunham, as well as from the automotive market, where TuneIn is now available on over 30 platforms.